Submarine telegraphy.



K. C. COX. suI/IARINE TELEGRAPHY. APPLICATION FILED MAR. 23. I9I5.

3?..9159375. Patented @et 26, 1915,

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KENWRCK GUK, 0F NRFOLK ISLAND,

sunnraninn 'rniinenarnm mmm specification of Letters raient Patented @en flpplication filed "March 23, wifi.` Serial .'lll'o. 16,5%.

To all whom t may concern:

Be it known that L ltniswmcn. @nono Coin subject oit .ltllis lldajestythe King of Engand`, residing at Norfolk'. lsland.j South Pacific7 electrician, have invented certain neu7 and useful lmprovernents in Submarine TelegraphyE o'f which the following is a s 'tication This invention relates to improvements in telegraphy in which a selenium relay is ein played and in which a movable beam of liejlit is controlled bythe moving coil ol' tlie recelvingi instrument such as by means ot a mirror carried thereby.

@ne feature of the present invention consists in the method of compensating for i e inertia oitl the selenium by means olf one or more inductive shunts rl further feature consists in arranging the cell or cells in series with the receiving instrument and a battery so that the current tending to llow through the instrument is opposed by another battery or hy mechanical means acting on the instrument as hereinafter described ln order that the invention. may be more clearly understood is hereinafter described with reference to the accompanying drawings in which t TFigure l? Fig. 2, Figa 3` andfllig. l are diagrams showing diierent arrangements of cells and connections hereinafter referred to.

ln one method et applying a pair of:

selenium cells to the purpose oil the inven-y tion the two cells e are, as shown in arms of a heatstone bridge, suitable resistances c el forming the other two arms.`

siphon recorder, or it may he a relay of any oit the well known types or any other apparatus that may be required for any particular purpose rlhe two selenium cells o; li are arranged with respect to the beam of light reectedV from the above mentioned mirror so that as shown each of them is partly illuminated and partly dark and so that as the beam of light is moved to one side or the otherY by. the deflection of the mirror a larger part of one cell becomes dark and a larger partI i. of the drawings7 arranged to form two of the other cell light. lt is usually bestj but not always essential, that when the mirror is at rest halt ot' each cell should be light and haltI dark. J@ilse3 in order to get the best results the two cells should be nearly. alike as regards their characteristic curvesp sensitivity and conductivityn rlfhe bridge is balanced by means of the resistances c d so that when the mirror is at rest no current passes through the instrument f. 'But any dellection ol the mirror varies the relative illumination ot the two selenium cells increasing' the conductivity oi one and reducing that oll the other so that the bridge balance is upset and a current passes through the instrument y@ in one direction or the other according to the direction in which the balance has been upset, that is, according to the direction in which the mirror was deflected.

lllith a given mean conductivity the greater the sensitivity oi the selenium. cells to changes in iliinnination the greater will be the current that passes through the receiving instrument f for a given movement of the mirror and its reflected beam ot light,

alsoot courserthe higher the voltage ot the battery the greater will be the ellfect produced by any given movement ot the miru ror. fllhus'v the etl'ect of the currents received trom the cable may be enormously magnilied, a very small movement of the mirror yproduced by the cable current causing considerable change in the relative conductivity of' the two selenium cells a` and conse* quently causing 'a comparatively large cur rent to pass the receivingf instrument f.

.This magnified ellect may be utilized so as to greatly increase the possible working speed of the cable, accordingn tc the well known principle that the smaller the current that can be utilized from the cable the greater the possible working speed, or it may.

be utilized to enable a coarse and simple receiving instrument or relay or other 1nstruinent to he used instead of the delicate `instrument that must be used when it (the receiving instrument) is connected directly vto the cable.

ln order to utilize to the best advantage very small movements of the reflected beam of li lit, l may either subdivide the selenium ce ls as shown in Fig. 2 of the drawings,or use a series of separate narrow cells, the beam, of light being/split up into bars so that each bar edects one pair of cells a a2 lll lili:

and i5 b2 in the manner above described and the separate pairs of cells being jolned up preferably as shown in such a way as to -add together the effects of the separate changes of illumination. In Fig. 2 two pairs of cells only are shown but the same principle may be extended to any number of pairs of cells.

By properly proportioning the width of the cells and of' the bars of light to the movement of the whole beam of light, the wholeof the sensitive surface of the cells may be brought under the influence of this movement. Witha pair of wide cells Where the movement of the beam of light is large it may be made to cover the whole surface of one pair of cells, but where the movement is small with regard to the width of the cells only a small part of the surface 4of each cell would. be affected by the change of illumination. Where there is no change of illumination there is no change of conductivity (temperature, voltage and other' conditions remaining constant), and therefore those parts of the cells which are not subjected to change of illumination are merely carrying current which is wasteful. I

In another method, shown in Fig. 3, of applying a selenium cell to the purposes of my invention-the cell a3 is arranged in series with a battery ef and the instrument f which it is required to affect. The selenium cell a3 is arranged with regard to the beam of light reflected from the mirror so as to be partly illuminated and partly dark, generally half of each. -With this arrangement a current will be always passing through the instrument f unless it is neutralized by an opposing current from another battery g provided for this purpose and which may be controlled by a suitable adjustable resistance it. Ordinarily the battery g and resistance z, are adjusted'so that the potential difference they produce at the terminals of' the instrument f exactly neutralizes the potential difference due to the battery e when the mirror and beam of light are as shown in their Zero position.7 Then any movement of the beam of' light will vary the illumination of the selenium cell a3, its conductivity will vary accordingly and the potential difference produced at the terminals of instrument f by the battery e will rise above or fall below that produced by battery g according as the conductivity of the selenium cell a3 is increased or diminished, and the receiving instrument f will thus respond to the changes in illumination of the cell a3.

It will be understood that instead of employing an opposing potential difference as above described to keep the current through the instrument f at zero when the beam of light is in its zero position, the same effect may be brought about by other means, and

especially by mechanical means. This arrangement is subject to the disadvantage that the characteristic curve of change of' conductivity of selenium with an increase of illumination is somewhat different to the curve obtained with a decreaseof` illumination, in the latter case the inertia is greater and the first, nearly instantaneous part of thecurve is shorter. In order to avoid this disadvantage two cells a wr are arranged as shown in Fig. 4 so that as the illumination of one is increased that of' the other is decreased. One cell a* is joined in series with a battery eg and a coil z' of the receiving instrument and the other cell a in series with the said battery e2 and another coil j of the instrument f2. The two coils t' and j are so arranged that the current from the battery e traverses them in opposite directions and they may be two windings ofl a siphon recorder coil, of a relay coil or of whatever instrument is used in connection with this invention.

Now, as the illumination of one cell say a is increased its conductivity is increased and an increase of current takes place in one of the coils z. At the same time the illumination of the other cell a5 is decreased and a decrease of current takes place in the other coil j. As the current traverses both coils z' j in opposite directions, the effect of the increase of current in the one coil is the same as that of a decrease in the other, so that for instance, if the coils are the two windings of a Siphon recorder coil the cflect of both windings on its movement will be the same. Zhen the-illumination of one cell a5 is increased that of the other cell a4 is decreased and the reverse effect produced on the instrument. /IVith this arrangement a compensating battery such as that previously describe at g in F ig..3 is unnecessary as the relative illumination and consequently the relative conductivity of the two cells (L4 af may be adjusted so that with the beam of light in its zero position as shown the opposing currents in the two coils t' j just balance each other. It may, however, sometimes be desirable to use compensating batteries c Z with series `resista'nces Z m in order to prevent an unduly large current from flowing through the two coils z' and 7' of the instrument. With two cells a* a5 thus arranged the' mean is obtained in the movement of the receiving instrument of the two curves. This mean is also obviously obtained with the arrangements hereinbefore first described with reference to Figs. 1 and 2 of the drawings. The latter arrangement may however in certain cases be the more advantageous, as by it the whole change of conductivity in the selenium cells L4 a5 becomes directly available to operate the receiving instrument.

It is obvious that the arrangement of cells rwasva last described with reference to Figs. 3 and 4 may be modified as lfirst described in the 'two previous arrangements Figs. l and 2 in order to make efiicientuse of very small movements 'of the beam of light; narrow cells, or sections of a cell being used and lthe beam of light being split up into bars.

Also the cells may be arranged in relation to the beam or beams of light either as shown in Figs. l, 2 and4 or as in Fig. 3 of thel drawings so that the beam of light passes from one small section of selenium to another Figs. 1, 2 and 4 or as in Fig. 3 so that the illumination of all the sections is varied simultaneously. A

In the application of this-'invention to submarine telegraphy it is necessaryuto eliminate the effect of the inertia of selenium, the first quick part of the change of conductivity being all that is of use. An inductive or magnetic shunt which is ordinarily connected across the receiving circuit to shunt o-tl slowly varying currents from the receiving instrument, and generally to sharpen the signals, is usually suiii cient for the purposes of this invention.

' The effect on the signals of the inertia of the selenium is to greatly increase their mounting or climbing up appearance, and this is entirely checked by suitable use of the said inductive shunt, the resistance in series with the shunt being made much lower than usual and the inductance being suitably adjusted.

In some cases l may use an inductive shunt across the receivinginstrument f of Figs. 1 and 2 or f1, f2, of Figs. 3 and 4, in addition to the one joined, in the usual tive shunt across the receiving instrument 'and have no inductive shunt across the main receiving circuit. v

'llhe inductive shunt across the receiving instrument is shown in the drawings as consisting of an inductive resistance p with a variable ohmic resistance r in series-therewith.

1. In telegraphy, a selenium relay comprising associated selenium cells arranged to form two arms of a Wheatstone bridge with suitable resistances inthe other arms to balance the bridge, a source of current connected across one diagonal of the bridge, and a ,receiving instrument and an inductive resistance in shunt one to the other connected across the other diagonal of` the bridge.

` 2. In telegraphy, a selenium relay having an inductive shunt around the receiving ining witnesses.

Y K. C. COX. lVitnesses: 1

R. E. NOBLE, A.. K. CAMPBELL. 

